First, I suggest emailing Vince at Iforged on the fastners since they are stainless steel and shoud NOT rust. Those wheels are indeed 3 piece like my Swifts , yours are just powdercoated black versus aluminum.
I would first wash them with P21S , Sonax, or Griots Wheel Cleaner
Then I would hand polish with "paint polishes" not "metal polish" on painted area (black)
You can metal polish the lips as long as not coated, easy by hand. Some suggest 0000 steel wool too.
Finally I would protect with DP or Poorboys Wheel Sealant.
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Now if you are really experimental on those discolored rivots and want to move carefully, then hears what I might try (No warranty offered or expressed"
1. Use a q-tip and swab the effected rivots with rust-remover being careful to keep away from paint as possible.
2. Wipe down rivots with damp (water only) qtip after to remove any excess rust remover and then dry well.
3. Coat with a good wheel sealant or perhaps Optimum Optiseal using another qtip as desired for good measure.
I would NOT suggest trying to powdercoat these yourself unless skilled in taking apart 3 piece wheels, there is usually a wire also used with each rivot to help with strength. Removing it might harm integrity of wheel and compromise your safety, I say clean 'em up first and see whatcha come up with !